(a) Field of the Invention
This invention relates to a method and an apparatus for the electrophoresis of a horizontal slab gel. More particularly, the present invention is concerned with a simple electrophoresis system for multiple agarose slab gels. Such a system allows for example, the separation of multiple DNA samples on four or more different gel slabs within the confines of a single apparatus, using only on power supply.
(b) Description of Prior Art
Agarose gel electrophoresis provides a simple, convenient, and inexpensive way to both analyze and prepare DNA molecules. Slab gels with multiple slots are used to perform the numerous assays required in the development and production of nucleic acid enzymes, markers, and cloning vectors. Physical mapping and analysis of DNA genomes as well as studies on the structure and function of DNA molecules also rely on such gels. Thus agarose gel electrophoresis has become an indispensable tool for nucleic acid researchers.
Relatively expensive electrophoresis systems may be fabricated according to known designs or may be purchased from different companies. However, the many useful applications of the technique often generate an unpleasant shortage of units and/or power supplies in the laboratory.
There are basically two types of electrophoresis apparatus: those which operate with vertical gels and the ones which use horizontal gels. There are presently available three popular types of apparatus wherein the gel is in a vertical tube. Bio-Rad Laboratories has a Model 155 which was designed by Loening about 1964 and is called a DISC Gel Electrophoresis System. With this system, we have an irregular migration from one tube to the other which means that it is difficult to compare the results obtained in one tube with those obtained in another tube, because proper alignment and adjustment in height should be made which creates all sorts of difficulties. Another apparatus sold by Bio-Rad Laboratories is called a Dual Vertical Slab Gell Electrophoresis Cell. This apparatus is excellent for use with a polyacrylamide gel. However, because it is also of the vertical tube type, it is difficult to adapt it to agarose gels which obviously do not adhere to glass. In essence, this apparatus is not practical with agarose gels.
It should be noted that a gel of agarose is used when relatively large molecules are involved. Since polyacrylamide produces a somewhat tight network it is acceptable for the electrophoresis of small molecules. However, large molecules do not penetrate into the gel. When small and large molecules have to be treated simultaneously, agarose is preferred, but it should be remembered that an apparatus which operates horizontally is then more practical.
The BRL Vertical Gel Electrophoresis System, model V 161 sold by Bethesda Research Laboratories Inc. is another apparatus which is available. It should however be noted that this one also operates as a vertical tube, with all the disadvantages mentioned above.
Finally, Bio-Rad Laboratories have a horizontal type of apparatus which is called Model HO. This device has to be used with one plate only which means that one power supply can only treat two gels.
There is therefore a need for an apparatus which is not complicated but is versatile enough to treat many plates at the same time by relying on the same power supply.